A tissue biopsy is the best way to diagnose necrotizing fasciitis. Cultures of the microorganisms can be taken either from the skin where the infection is spreading or from deeper tissues during surgical debridement. Gram staining can be done to the biopsied tissue in order to determine what type of organism it is and what the best treatment will be. Radiographic studies can show the presence of subcutaneous gases and CT scans can find the area involved by locating the necrosis. Combined with the information from a clinical assessment, MRI's can also determine the areas of necrosis and if surgical debridement is necessary. The first set of pictures below are CT scans of necrotizing fasciitis. The top two pictures in the second set are MRI's of a left forearm and the bottom two are MRI's of a left leg with necrotizing fasciitis.
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